Thermostatically controlled switch



A. M. YOUNG THERMOSTATICALLY CONTROLLED SWITCH Dec. 8, 1931. 1,835,552

Filed Jan. 8, 1930 Z Z6 44 Z4 I I {6 4 a T? 1 5 1 i5: Li j +3273 E L5 l7 6 5 v INVENTOR /4//0W flZ)6U/7j ATTQRNEY5 Patented Dec. 8, 1931 UNITEDSTATES PATENT OFFICE ALLAN M. YOUNG, OI MIEBIDEN, CONNECTICUT, ASSIGNORTO MANNING, BOWMAN &

00., OF MEBIDEN, CONNECTICUT,

A CORPORATION OF DELAWARE THERMOSTATICALLY CONTROLLED SWITCH Applicationfiled .Tanuary 8, 1930. Serial No. 419,238.

My invention relates to a thermostatically controlled switch, and hasspecial reference to a device of this character which is particularlyadapted for use on electric sad irons and other electrically heatedhousehold utensils.

One of the objects of the present invention is to provide a device ofthis character which is simple in construction and reliable and accuratein operation.

Another object of the invention is to pro vide a device of thischaracter which effects a quick make and break of the circuit withoutdanger of arcing.

vide a novel and improved device of this character which ma be easilyadjusted to meet different conditions. 1 The several features of theinvention wherebythe above-mentioned and other objects may be attained,will be readily understood from the following description andaccompanying drawings, in which:

Flgure 1 is a plan view of a thermostat1cally controlled switchembodying the features of my invention in their preferred form;

Fig.2 is a detail sectional view taken on the line 22 of Fig. 5; 1 Figs.3 and 4 are views on an enlarged scale corresponding to a portion ofFig. 1 but showing operative parts of the switch in different positions;and

Figs. 5 and 6 are sectional Views taken respectively on the lines 5.5and 66 of Fig. 1. The thermostatically controlled switch illustrated inthe drawings is mounted on a base plate 2 which is adapted to besuitably secured upon a wall or other member 4 that may-constitute a artof an electric sad iron or other electrical y heated household utensil.As shown, the base is secured to the member 4 by means of rivets 6, andis insulated from the member 4 by a sheet of mica 8 and washers 10 ofmica for-the heads of the rivets the rivets being spaced from the wallsof the apertures through'which they extend in the base plate 2.

riveted or otherwise secured to anupstandis flexed outwardly asindicated by broken lines in Fig. 1. The usual rotatable cam member 16may be associated with the bi-metallic element to regulate the degree oftemperature at which the switch Will open, the cam being adapted to beforced against the outer side of the bi-metallic element.

In the illustrated construction, a channelshaped carrier 18 has one wallsecured by rivets 20 to the inner side of the free end A further objectof the invention is to pro of the bi-metallic element 12. An adjustingabutment screw 22 is screw-threaded through the free end of thebi-metallic ele- .ment and through the adjacent wall of the carrier 18with its inner end directed toward the other sidewall of the carrier.The latter side .wall of the carrier has terminal contact screws 24mounted therein with the screws suitably insulated therefrom and fromeach other, the heads of the screws being at the inside of said wall.

A leaf spring 26 extends between the abutment '22 and the heads of theterminals 24 and has its ends held in the upstanding arms of a U-shapedcradle 28 which may be made of phosphor spring metal. The ends of saideaf spring are so held as to cause the spring to be bowed so-that uponmoving the spring in either direction pastits dead center, the

spring will snap into bowed position on one side or the other of itsdead center, the arms of the spring metal cradle 28 yielding during suchsnapping action. The center of the leaf spring carries a stud 30 on theouter end' of which 1s secured a contact member 32 of silver which whenthe spring is in one bowed position bridges the heads of the terminalcontacts 24, the contact disk 32 being loosely secured on the stud*'*80so as to permit it to adjust itself to the two contacts.

With this construction,-the contact 32' is normally in firm bridgingengagement with the heads of the terminal contacts 24. During theoutward flexing of the free end of the bi-metallic element as thetemperature rises, the terminal contacts are moved so as to act throughthe bridging contact to force the center of the bowed spring toward thebimetallic element, and upon the temperature reaching a predetermineddegree, the spring is thus forced rearwardly past its dead center,whereupon it immediately snaps so as to quickly disengage the bridgingcontact 32 from the terminal contacts 24, thus opening the circuit. Thissnapping movement of the leaf spring is limited by the engagement of therear end of the stud 30 with the end of the adjusting screw 22. Duringthe lowering of the temperature, as the free end of the bi-metallicelement moves toward its normal position, the abutment screw 22 forcesthe bowed leaf spring in the opposite direction until it passes its deadcenter, whereupon the spring snaps to quickly move the bridging contact32 into bridging engagement with the terminal contacts 24.

Owing to the arcuate movement of the terminal contacts 24 from normalposition to a point where the leaf spring snaps to disengage thebridging contact from the terminal contacts, the heads of the terminalcontacts wipe over the surface of the bridging contact, and this wipingaction increases as the contacts approach the position where breaking ofthe circuit is effected. In order to increase such Wiping 'actionbetween the bridging contact and the terminal contacts previously tobreaking the circuit, the points of connection of the ends of the leafspring with the arms of the cradle28 are arranged in a line at asuitable angle, as shown in the drawings preferably three degrees, tothe bimetallic element so that as the leaf spring is forced toward itsdead center previously to snapping away from the terminal contacts, thecenter of the leaf spring and consequently the bridging contact tends tomove in a direction gene-rally transverse to the heads of the terminalcontacts. This wiping action between the terminal contacts and thebridging contact has been found to effectively prevent arcing during theseparation of the contacts.

' By adjusting the screw 22 toward and from its point of engagement withthe leaf spring, the degree of movement of the bi-metallic elementtoward its normal position necessary to effect closing of the switchduring the lowering of temperature may be varied as desired, and thusthe device may be adjusted so as to be extremely sensitive to anylowering of temperature after the switch has been opened.

It will be apparent that my improved device is of simple and cheapconstruction; may be easily and conveniently applied to electric sadirons and other electrically heated household utensils; operates withoutdanger of arcing; and may be easily adjusted so as to insure quickbreaking of the circuit when the temperature reaches a predetermineddegree and quick closing of the circuit when there is any appreciablelowering of temperathe class described having, in combination, a

bi-metallic element having one end fixed and its other end free to flexunder changes 1n temperature, an abutment carried by the free end ofsaid element, terminal contacts car ried by the free end of said elementand spaced from said abutment, a bowed leaf spring adapted to snap as itis forced by its dead center in opposite directions, a contact carriedby said leaf spring and adapted to bridge said terminal contacts wherebywhen the free end of the bi-metallic element is flexed in one directionthe terminal contacts through the bridging contact forces the leafspring past its dead center so as to cause it to snap into engagementwith said abutment to disengage the bridging contact from the terminalcontacts and when the bi-metallic element is flexed in the oppositedirection said abutment forces the leaf spring past its dead center soas to cause it to snap 'to re-engage the bridging contact with theterminal conspring being in a line arranged at a suitable angle to saidbi-metallic element so that as the spring is moved toward its deadcenter to disengage the contacts, the contact on the spring tends toWipe across the terminal contacts.

2. A thermostatically controlled switch of the class described having,in combination, a bi-metallic element adapted to flex under changes intemperature, an abutment carried by said element, a contact carried bysaid element and spaced from said abutment, a bowed leaf springextending between said abutment and said contact and adapted to snap asit is forced by its dead center in opposite directions, a contactcarried by said leaf spring and adapted to engage said first mentionedcontact whereby when said bimetallic element is flexed in one directionsaid contacts force the leaf spring past its dead center so as to causeit to snap mto engagement with said abutment to disengage that asthespring is moved toward its dead center to disengage the contacts, thecontact on the spring tends to wipe across the contact carried by saidelement.

3. A thermostatically controlled switch of the class described having,in combination, a bi-metallic element having one end fixed and its otherend free to flex under changes in temperature, an abutment carried bythe free end of said element, terminal contacts carried by the free endof said element and spaced from said abutment, a support, a bowed leafspring extending between said abutment and terminal contacts and havingits ends secured on said support to permit the center thereof to snap asit is forced by its dead center in opposite directions, a contactcarried by said leaf spring and ada ted to bridge said terminal contactswhere y when the free end of the bi-metallic element is flexed in onedirection the terminal contacts through the bridging contact forces theleaf spring past its dead center so as to cause it to snap-intoengagement with said abutment to disengage the bridging contact from theterminal contacts and when the bi-metallic element is flexed in theopposite direction said abutment forces the leaf spring past its deadcenter so as to cause it to snap to re-engage the bridging contact withthe terminal contacts, the points of engagement of said ends of the leafspring with said support being on a line arranged at a suitable angle tothe bimetallic element so that as the bridging contact is moved by theterminal contacts to move the leaf spring past its dead center, thebridging contact tends to wipe over the terminal contacts previously tothe disengagement of the bridging contact from the termi nal contacts.

4. A thermostatically controlled switch of the class described having,in combination, a

bi-metallic element having one end fixed and its other end free to flexunder changes in temperature, a channel-shaped carrier having one sidewallsecured to a side of the free end of said strip, an adjusting screwextending through said side wall, terminal contacts carried by the otherside wall of said carrier, a U-shaped cradle, 11 bowed leaf sprinextending generall parallel with sai bimetallic element 'aving its endsheld b the ALLAN M. YOUNG.

signed my sides of said cradle to permit the center t ereof to snap asit is forced by its dead center in opposite directions, a contactcarriedby said leaf spring andadapted to bridge said terminal contacts wherebywhen the free end of the bi-metallic element is flexed in one directionthe terminal contacts through the brid 'ng contact force the leafspringpast its dea center so as to cause it to snap into engagement withthe end of said adjusting screw to disengage the bridging contact fromthe terminal contacts and when the bimetallic element is fixed in theopposite direction said adjusting screw forces the leaf

